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Thesis (M.S.)--Rochester Institute of Technology, 1993. / Typescript. Includes bibliographical references.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016. / Optimum communication can only be achieved with a very sensitive front-end section in the receiver on a satellite because the transmitted signal from the ground station must travel hundreds of kilometres through the earth's atmosphere to a low earth orbit (LEO) satellite. This dissertation presents the design of the front end section of the receiver suitable for use in a nano-satellite. Specifically, various transistor technologies are evaluated by designing five low noise amplifiers to determine the optimum performing amplifier. The bandwidth of the front end section was controlled by designing coupled line microstrip filter. For consistency, the same design technique was followed in the design of each LNA. Simulations were performed and the results were compared to the actual measured results of the constructed amplifiers to facilitate conclusions to be made. Design specifications for the LNAs were obtained from the F'SATI Space CubeSat Programme Technical Specification document. To control the bandwidth of the front end section, various types of band-pass filters were investigated, resulting in a coupled line band-pass filter being simulated and implemented. The simulated results were compared to the measured results of the constructed filter. In the final stage of this dissertation, comparisons of each amplifier’s performance were made, resulting in the final recommendation for this project.

The analysis and design of a hybrid-coupled tunnel-diode amplifier is described, considering both the hybrid junction and the tunnel-diode circuitry. The fundamental theory of the tunnel diode is reviewed. The hybrid junction is in the form of a strip-line directional coupler which makes use of the inherent contra-directional coupling between two adjacent transmission lines. A complete analysis of the frequency dependence of the response of such a coupler is given. The amplifier is realized using the coupler and a pair of matched diodes terminating mutually isolated ports. To optimize the performance of this type of amplifier the design of the coupler is integrated with the design of the diode circuit. In doing so, account is taken of the frequency dependence of the hybrid junction, an aspect of the problem which has not been treated in the literature. As an example, an amplifier covering the VHF television channels is designed, and experimental results of a working model for a 50-ohm system are presented. The amplifier uses the periodicity of the directional coupler to provide two pass bands spanning Channels 2 to 6 (54 to 88 Mc) and Channels 7 to 12 (174 to 216 Mc), respectively. The two GE lN2939A tunnel diodes used for the amplifier provide a gain of 7.8 db ± 0.3 db for the lower band and 8.9 db ± 0.45 db for the upper band. The maximum input VSWR for the lower and upper bands are less than 2.3 and 3.2, respectively. The theoretical noise figure for a bias current of 0.7 ma is 3.79 db. It is found that the experimental results are in general agreement with the theory. Suggestions for improvement are given in cases where discrepancies do occur. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

In the iterative method for producing maximally-flat response for the multicavity klystron amplifier, a choice must be made in allocating poles to cavities. In this thesis, a method is described for selecting the tuning pattern which will give flat response with maximum gain for a specific multicavity klystron. The iterative method for multicavity klystron amplifiers is extended, to tubes with up to six cavities. It is shown that the optimum tuning pattern has an appreciable advantage in gain over the alternative choices. The practice of allocating the highest-frequency pole to the penultimate cavity is justified, at least for relatively short tubes. Illustrative numerical tuning designs for four-, five- and six-cavity klystron amplifiers with different tuning patterns are given to verify the method. The restrictions of small-signal fundamental-mode theory apply throughout the thesis. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

This thesis describes the theoretical adjustment of the tuning of multicavity klystron amplifiers for prescribed frequency response. The method used is an iterative process developed at Stanford University in 1952. The purpose of the investigation was to test the applicability of the iterative method to the design of microwave amplifiers. The rational function representation of klystron amplifier response is described and it is shown that for physical realizability the zeros of transmission must be dependent on the poles of transmission. An iterative numerical method is developed for simultaneously fulfilling the prescribed response conditions and the physical realizability condition. Illustrative numerical designs of four- and five cavity klystron amplifier tuning are given which verify the method. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The theory of the magnetic amplifier and other carrier amplifiers is put on a general mixer basis. The amplifiers are compared from this common basis and paths of further development indicated. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This thesis discusses the design of a stable 150 KW 23MHz RF system for the TRIUMF CRM cyclotron. The required characteristics of this system are presented with emphasis on the amplitude and phase modulation constraints. The composition of an amplifier system satisfying the power, bandwidth and noise requirements is discussed. Both the initial and present PA designs are presented, as is the design of the driver amplifier. Also included is a discussion of the choice of tubes and RF circuits. The usefulness of feedback control in satisfying the RF stability requirements is shown. The conditions a stable feedback system must satisfy are also given. Two amplitude control systems (drive control and screen control) are designed using Bode techniques. A digital simulation of these systems using an electrical analogue is presented. Implementation and results are discussed. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

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